Jan.
6, 2005 — In addition to causing tremendous loss to human life and property,
the tsunami that devastated
coastal communities along the Indian Ocean on Dec.
26, 2004, may have also caused extensive environmental damage throughout
the nearshore marine ecosystems in this region. At
this time, it is difficult to know just how far offshore the damage
extends and little research has focused on this topic.(Click
NOAA image for a larger view of the effects of the September 1, 1992,
tsunami on the near coastal shore of Leworahang, Indonesia. The measured
runup height at this location was 36 feet. The unofficial height was
46 feet. A paved road comes to an abrupt halt at the edge of the vertical
cliff. Click here for high resolution
version, which is a large file. Please credit "NOAA.")

NOAA
researchers have found that tsunamis usually have little, if any,
effect on deep open ocean waters, however, they
rapidly intensify and become highly destructive once they enter shallower
coastal waters—exactly where this area’s valuable coral reefs
are known to thrive. Nearshore mangroves and sea
turtle nesting areasare also likely to have
been inundated by the powerful tsunami waves. Unfortunately, many of
these habitats have already been dramatically affected by tourism, overfishing
and pollution, so a natural disaster of this magnitude would only add
to an already threatened nearshore marine environment.

“The
nearshore marine ecosystems affected by the recent Indian Ocean tsunami
are likely to have experienced direct damage from severe wave action
and indirect damage from sedimentation and excessive amounts of debris,”
said Rusty Brainard, chief of the coral reef ecosystem division within
the NOAA Pacific Islands Fisheries
Science Center.

It is likely
that coastal beaches and nearshore land areas devastated by this tsunami
could be restored within a few years, but the most severely impacted
nearshore marine ecosystems could take centuries to fully recuperate.
The future of marine resources in the region could also be dramatically
affected, especially the coastal fishing and tourism industries.

Direct
ImpactsThe
direct impact of severe wave energy on shallow nearshore habitats (including
coral reef ecosystems, seagrasses and mangroves) could be extensive
but also depends on the amount of wave energy these ecosystems are normally
exposed to. Areas normally exposed to significant wave energy from large
swells or tropical storms are less likely to be severely impacted. On
the other hand, shallow bays typically protected from high wave action
could have suffered more extensive damage.

Damage by wave energy is also species specific. Some species of coral,
algae and other marine invertebrates are extremely delicate and cannot
withstand turbulent high energy environments. As a result, these species
would be particularly susceptible to the damaging wave energy generated
by this tsunami.

Extensive
damage to nearshore estuaries, mangrove and seagrass habitats — many
of which could have been completely torn free of their roots — would
also be expected. However, these habitats would be expected to recover
over several months or years.

This powerful
tsunami could have substantially altered some shallow water benthic
habitats, reducing their effectiveness as nurseries and shelters for
fish and benthic organisms — organisms living on, attached to, or burrowing
in the sediment of the ocean floor. As a result, some nearshore fisheries
could be impacted by very low recruitment success over the next few
years. Unfortunately, such impacts could ripple
through the entire food chain for decades, however, they will not likely
cause lasting impacts.

Indirect
ImpactsA major indirect impact of the tsunami on nearshore marine
ecosystems includes sedimentation from extreme runoff and the churning
up of coastal silt, sand and organic matter. Some ecosystems could have
been buried by sediments flushed into shallow nearshore environments.
For areas normally exposed to high wave energy or strong currents, this
sedimentation will probably be washed away over several weeks or months,
depending on degree of sedimentation. In more protected areas (not typically
exposed to significant wave energy or currents), it could take years
or decades for the ecosystem to recover.

Other major
indirect damage could have been caused by excessive amounts of debris,
including buildings, vehicles (cars and buses), boats, refrigerators
and/or any large, non-buoyant object that ended up in the shallow marine
environment. When debris of this type is caught up in strong nearshore
waves and current, it can easily 'bulldoze' corals and other benthic
substrates (i.e., ocean bottom).

Many of
these items and other debris flushed out to sea could have contained
hazardous chemicals, oils, paints, freons, cleansers, etc., which could
be deposited in and cause stress to nearshore marine ecosystems. These
stressors could cause disease in corals, algae, fish and other invertebrates.
Because most benthic organisms are filter feeders, this group of organisms
is likely to be most severely affected. Unfortunately, these impacts
could be long-lived and not become apparent to researchers for months
or even years.

Debris,
such as lost fishing gear (e.g., lines, nets, traps, etc.) from sunken
and damaged boats could entangle and/or drown protected species (marine
mammals, turtles, etc.). Because fishing gear is often composed of plastic
and/or other non-biodegradable materials, it can last in the marine
environment for years or even decades. Metal objects deposited into
the nearshore marine environment can also trigger blooms that often
outcompete corals for benthic substrate.

NOAA
Fisheries is dedicated to protecting and preserving the nation's
living marine resources and their habitat through scientific research,
management and enforcement. NOAA Fisheries provides effective stewardship
of these resources for the benefit of the nation, supporting coastal
communities that depend upon them, and helping to provide safe and healthy
seafood to consumers and recreational opportunities for the American
public.

NOAA
is dedicated to enhancing economic security and national safety through
the prediction and research of weather and climate-related events and
providing environmental stewardship of the nation’s coastal and marine
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Department of Commerce.